Abstract

A significant problem which limits the practical application of Ti:LiNbO₃ devices at shorter wavelengths (λ ≤ 1 μm) is that of index instabilities caused by the photorefractive effect, which have been observed at guided power levels as low as 30 μW at λ = 830 nm [1]. A possible solution to this is to use waveguides formed by proton-exchange, which have been reported to handle power densities at least four orders of magnitude greater [2]. However, some undesirable effects have been observed in these waveguides, including long-term index instability, and reduced electro-optic efficiency [3]. We recently reported [4] that by using a dilute-melt (DMPX) process, these effects can be overcome, and we obtained Vπ's between 1.7 and 2.7 V for an 8 mm-long push-pull interferometer at 830 nm wavelength, comparable with titanium-indiffused devices. Here, we report that travelling-wave modulators formed by DMPX behave as expected, and show no measurable degradation in microwave characteristics as a result of the increased photoconductivity of the waveguides.

© 1986 Optical Society of America